Refrigerating system



NOV. 21 1939. w- I 2,180,447

' REFRIGERATING SYSTEM v I Filed Oct. 2'7, 1937 v 4 Sheets-Sheet l l l l v I I Nov. 21, 1939. F WHITNEY 2,180,

iREFRIGERATING SYSTEM Filed Oct. 27, 1957 4 Sheets- Sheet 2 Nov. 21, 1939.

L. WHITNEY REFRIGERATING SYSTEM 4 Sheets-Sheet 3' Filed Oct. 27, 1957 1939- L. F. WHITNEY REFRIGERATING SYSTEM Filed oct. 27, 1957 4 Sheets-Sheet 4 Patented Nov. 21, 1939 i 2,180,447

" UNITED STATES PATENT OFFICE REFRIGERATING SYSTEM Lyman F. Whitney, Cambridge, Mass, assignor, by mesne assignments, to Stator Corporation, a corporation of Rhode Island Application October 27, 1937, Serial No. 171,325

21 Claims. (Cl. 62-115) This invention relates to an improved refriger- As taught more particularly in my copending ating. apparatus of the general type disclosed in application Serial No. 207,267, filed May 11, 1938, the United States Patent No. 1,761,551 to Eastan aqueous refrigerant comprising a solution of man A. Weaver and in my United States Patent a suitable anti-freeze agent in water may con- No. 1,756,802. veniently be employed in a system of this char- 5 The above-identified patents disclose a system acter when it is desired to have cooler temperaemploying water as a refrigerant and mercury as tures substantially below 0 C. Among such antiapropellant. While water has very advantageous freeze agents are methyl Cellosolve, either as characteristics for this. purpose, it often is desircommercially obtained or in a chemically pure.

able to provide a refrigerant which has a lower form, ethylene diamine and morpholine. When 10 freezing point. Furthermore, while water and a system having conventional steel walls is emmercury are liquids which are substantially imployed, I prefer'to use an anti-freeze agent havmiscible under all ordinary conditions, I have ing its major part consisting of methyl Cellofound that under certain operating conditions solve and preferably including a minor part of very fine particles of mercury, such as are 'proethylene diamine. If desired, a'small percentage 15 vided by mercury vapor or by mercury fog, when .of morpholine may be included in such. an anticontacting water, tend to assume an extremely freeze agent. I have found, however, that the finely dispersed condition in the water to form employment of methyl Cellosolve as an antitherewith a more or less stable sludge. For exfreeze agent substantially aggravates the tendency ample, when some mercury passes with the water toward the formation of heavy deleterious sludge, 20

vapor to the refrigerant condenser, a sludge may both in the form of sludge suspension and in be formed. This sludge drains to the cooler, the form of sludge deposit. When even a small where it may'gradually become heavier as more percentage of ethylene diamine is employed, sludge is received from the condenser. Furthereither with water alone or with water and an I 5 more, mercury vapor or fog may occasionally pass anti-freeze agent such as methyl Cellosolve, the directly from the aspirator mixing chamber into sludge suspension is thinner and the sludge dedirect contact with the water in the cooler, thus posit more capable of flowing. causing the formation of a sludge. The tendency The present invention affords improved refrigto form sludge is aggravated in a system having crating systems of this general character in which walls of ordinary steel. The proportions of merthe parts of the refrigerant circuit are arranged 30 cury and water in the sludge may vary widely, to permit the eflicient operation of the system and the sludge in many respects resembles mud. either with an aqueous refrigerant comprising I call suspension of mercury in water a sludge substantially pure water or a solution of an antisuspension. Depending upon operating condifreeze agent in water. Such a system is arranged tions, this suspension may be either lean or rich so that sludge which has collected in the moler in the mercury. If only a thin sludge suspension may be broken up so that the mercury returns exists in the system, the efiects are negligible. to its normal state, thereby preventing the col- However, the mercury tends to settle in such a lection of a substantial quantity of deleterious body of sludge suspension; the settling mercury sludge in the system and thus substantially 40 may not coalesce, but rather may form a mud-like avoiding the disadvantages described above.

sludge deposit. Should the factors that cause Afurther aspect of the present invention relates the original suspension continue to be present, to the arrangement of the cooler and associated they cause the formation of further sludge suspiping to facilitate the vaporization of the repension from which additional mercury settles, frigerant at a low pressure, such an arrangement 5 thus augmenting the mud-like deposit. When being especially advantageous when an antithe sludge suspension is relatively rich in merfreeze agent is employed which tends to impede cury, the tendency to form the mud-like deposit vaporization. For example, during operation of is increased. Any type of sludge except a thin the system, when methyl Cellosolve is employed sludge suspension is deleterious because it inas the anti-freeze agent, the proportion of the I volves a collection of mercury where it is not methyl Cellosolve at the surface of the liquid 50 needed, thus materially increasing the total body in the cooler tends to be somewhat greater amount of the relatively expensive mercury rethan in the remaining portion of that body and quired in the system. A sludge deposit is alsothis layer of stronger solution does-not vaporize delete Since t tends to p de free circulaas readily as a mixture having an average contion of the fl s through p p centration of the methyl Cellosolve.

The present invention afiords arrangements of piping to cause agitation of the solution in the cooler, thus tending to cause the solution to be more uniform and aiding vaporization. Such an arrangement may also be conveniently employed to permit the cooler or evaporator and the water condenser to be near the same level so that the system may be compactly installed in a refrigerator casing of conventional height.

A further feature of the present invention relates to the provision of a chamber associated with an interstage cooler of the type disclosed in my prior United States Patent No. 1,756,802, to facilitate the collection of condensed mercury in this portion of the system and to direct the same to the trap assembly associated with the cooler and to the purger, which is effective in exhausting non-condensable gases from the system.

In order to break up sludge, which sometimes appears in a system of this character, a drum may be arranged to receive sludge which has collected in the cooler, this drum being connected to one of the aspirators, as the first-stage aspirator, so that the volatile refrigerant maybe'drawn from the sludge, the mercury being dried to cause it to coalesce, whereupon it may drain to the lower part of the system. Preferably the trap connecting this drum to the cooler may be provided by a pipe of relatively large cross section to permit the flow of the sludge to the drum under a moderate liquid head.

Such' a drum and the associated piping may also be arranged to prevent freezing to a seriously objectionable extent of the refrigerant returning from the refrigerant condenser to the cooler or evaporator. Thus when freezing does occur in this portion of the system, the returning solution is directed into the drum and a portion of the pumping effect of the propellant is diverted to cause the withdrawal of vapor from the drum. Accordingly there is less tendency to draw vapor from the cooler, and the temperature of the latter automatically tends to rise so that ice which has formed in piping connecting the condenser to the cooler may melt.

The drum is also advantageous since it may involve the automatic maintenance of the boiler pressure within relatively close limits, despite a considerable variation in the amount of heat being supplied to the boiler, such an arrangement of the liquid body. Associated with this piping may be suitable means to introduce the returning condensate into the cooler in such a manner as to break up the cold layer even if freezing occurs in the piping through which the condensate is preferably supplied to spray onto the liquid surface.

The arrangement of this piping and the associated-parts of the system maybe such that the height of the liquid column which balances the difference between the cooler and condenser pressures is automatically varied in accordance with.

variations in the pressure diflerential between the cooler and the condenser. The piping through which the condensate is supplied to the cooler may be combined with the, means to receive sludge from the cooler and to supply the same to the drum where the mercury and refrigerant separate and where vaporization of the refrigerant occurs if the refrigerant cann'ot flow to the cooler from the condenser due to the freezing of refrigerant in the piping between these parts of the system.

In the accompanying drawings:

Fig. 1 shows somewhat diagrammatically the arrangement of a refrigerating system employing a heavy high boiling point propellant, such as mercury, and an aqueous refrigerant, and exemplifying the novel features of the present invention;

Fig. 2 is an elevational view of the first stage aspirator and funnel assembly;

Fig. 3 is a horizontal section of the same indicated by line 33 of Fig. 2;

Fig. 4 is a view similar to Fig. 2 but showing the second stage aspirator and funnel assembly;

Fig. 5 is a section on line 55 of Fig.4;

Fig. 6 is an enlarged view of the trap assembly associated with the cooler, the food compartment housing being shown in dot and dash lines;

Fig. 7 is a view similar to Fig. 6 with the liquids shown at different levels in the trap assembly;

Fig. 8 is a broken elevational view with parts in section, showing the purger assembly;

Fig. 9 is a sectional view with parts in elevation showing the boiler, the burner and associated portions of the apparatus;

Fig. 10 is a section indicated by line llllfl of Fig.

Fig. 11 isa detail view, partly in elevation and partly in section, of a portion of the system; and

Fig. 12 is a view similar to Fig. 6, but showing an optional trap assembly.

A system of this type may comprise a boiler I having a suitable heating element 2, such as a gas burner, provided with a draft-inducing flue 3 through which exhaust gases are vented. Mercury vapor passes from the boiler I through a riser pipe 5'to branches 5* and 5 which are connected respectively to the first and second stage aspirators. The first stage aspirator may comprise a nozzle 6 (Figs. 2 and 3) from which mercury vapor passes at relatively higli velocity into a mixing chamber 1; The latter is connected by a vapor duct 8' to the cooler or evaporator II. The latter may contain a body of liquid refrigerant, such as water, and a suitable anti-freeze ingredient. Vapor is drawn through the pipe 8 to the mixing chamber 1 and the mixed propellant and refrigerant vapors pass into the funnel II, where the refrigerant is compressed and the mer cury is condensed. The funnel preferably may have proportions of the order shown in Fig. 3, this advantageous form of funnel being more fully disclosed in my copending application Serial No. 177,489, filed December 2, 1937. The condensed mercury flows from the lower end of the funnel I 2 into a drain l4, while the vapors pass into a pipe coil or loop I6 which is provided with cooling fins and forms an interstage cooler.

The latter is connected to an interstage drum or chamber I9 which has a substantially larger cross section than the interstage cooler pipe l6, so'that the velocity of the vapor flowing through the drum is reduced, thus enhancing the tendency of condensed mercury particles to settle and collect at the lower part of the drum. The drum I 9 may conveniently be provided with a bottom wall which inclines upwardly from its opposite sides to an intermediate ridge.' Part of the condensed mercury collecting on this lower wall of the drum is directed to the pipe 20, while the remainder of the condensed mercury flows into the duct 2| which receives the refrigerant vapor. The pipe 20 contains a suitable bof liquid mercury forming a trap to preclude th; flow of vapor from the drum through this; pipe, the end of the .pipe being connected to the drain l4, so that mercury from this pipe may overflow into the drain and to parts of the system that will be described.

The compressed and cooled refrigerant vapor passes from the pipe 2| into the second stage mixing chamber 22 (Fig. 5) into which a stream of mercury flows at high velocity fr cm the nozzle 23. This propellant stream is effective in causing further compression of the refrigerant vapor in the second stage funnel 25. A drain2l receives condensed mercury from the funnel 25 and from the drain M.

The first stage funnel l2 and the second stage funnel 25 preferably are provided with cooling fins l3 and l3 respectively, being disposed in jackets l2 and 25 which are connected respectively by ducts l2 and 25 to condensers or heat dissipators l2 and 25. Each of the jackets may contain a bodyof liquid coolant, such as alcohol, which may be vaporized by the heat of the corresponding funnel, the vapor rising to the corre* sponding condenser It or 25 and the condensate draining back from each condenser to the corresponding jacket. Preferably the iackets and condensers may be evacuated before operation of the apparatus is started, so that the coolant vaporizes and condenses at a lower temperature than would be the casewere these parts of the system at atmospheric pressure when the system was not in operation.

The compressed refrigerant vapor passes upwardly from the funnel 25 through the duct 29 to the refrigerant condenser 30-. In practice a portion of the pipe 29 may be arranged in heat transfer relation to a warm part such as the riser branch 5& or the'interstage cooler l6 and the pipe may be provided with a plurality of internal protuberances or fins. Such fins may have openings therein to prevent pocketing of condensed mercury. The arrangement of the pipe 29 in this manner substantially prevents mercury from passing into the refrigerant condenser 30 and accordingly reduces the quantity of sludge formed by the condensate passing from the condenser back to the cooler H. The condenser 39 may be of any suitable form, being either air cooled or water cooled, as desired. For example, this condenser might be of the type disclosed in my copending application Serial No. 171,647, filed October 29, 1937. As shown herein for purposes of illustration, the condenser 30 comprises a conventional pipe assembly with cooling fins 3|.

A chamber or drum'32 preferably is located at the end of condenser 30 which is remote from the pipe 29. A pipe 44 has an open end communicating with this chamber and receives noncondensable gases therefrom.

The lower portion of the condenser chamber freshly condensed weak refrigerant into the cooler so that it tends to break up or dilute the strong solution. For this purpose the pipe 34 may have its lower end connected to an upwardly extending duct 35 (Fig. 6). The upper end of the latter 1:. connected to a tube 36 of small diameter, which communicates with the interior of the cooler H above the surface of the liquid contained therein.

The lower parts of the pipe 34 and of the returning refrigerant is high relative to the temperature of the cooler, and since the pressure in the cooler is low, some vaporization of the refrigerant occurs induct 35. Accordingly. the refrigerant passes through the tube 36 in the form of separate slugs or separate bodies of liquid, which are propelled by bodies of vaporized refrigerant. Thus the returning refrigerant may be sprayed onto the surface of the liquid refrigerant in cooler II. Accordingly, the stronger anti-free solution, which tends to collect at the top of the liquid body, is diluted and agitated, so that vaporization can more readily take place at the surface of the liquid body.

Furthermore, I have found that, for example, when water alone is employed as a refrigerant, a thin cold film tends to form at the surface of the liquid body in the cooler. temperature lower than the mean temperature of the cooler, the refrigerant at the surface accordingly being less volatile than the remainder of the liquid body. The arrangement of the tube 36 to spatter slugs of refrigerant causes this cold film to be broken up and accordingly this arrangement is also advantageous in enhancing. the cooler efficiency even when an anti-freeze agent is not used.

Under certain conditions, particularly due to the restricted diameter of tube 36, the returning refrigerant may freeze in this tube so that the condensed refrigerant cannot return to the evaporator H in the manner which has been described. To provide for such an eventuality, I provide means which permits the by-passing' of the refrigerant to the cooler. For this purpose, the lower end of pipe 34 is connected to an inclined. tube 40, the upper end' of which has a vertical continuation 42 that may extend above the liquid level in the cooler and have a connection with a downwardly extending pipe 43 which is connected to a duct 44, which also serves as a drain. The upper end of duct 44 communicates with the lower part of the cooler II, and

stray propellant particles may drain from the cooler through this duct. When'freezin'g occurs in the tube 36, liquid refrigerant will depress the mercury at the juncture of pipes 34 and 40, so that the refrigerant may rise in the duct portion 42 and pass into the portion 43 flowing from the latter into the drain 44. The returning refrigerant, which may be a relatively weak solution, passes into the stronger solution in duct 44 before reaching the cooler. I have found that the introduction of the weak solution in this'manner tends to prevent freezing and also aids in breaking up the cold film at the surface of the liquid body, so that this arrangement, wh le particularly advantageous when an anti-freeze agent is employed in the refrigerant, may also be used when a refrigerant such as pure wateris used. In fac such an arrangement gives an effect comparable to that afforded when the refrigerant is spattered from the tube 35 into the cooler..

The lower part of duct 44 provides a shallow This film has a As condensed refrigerant collects trap communicating with a drum 50 (Fig. 11). The duct 44 preferably has a relatively large diameter. A trap 5| connects this shallow trap to the second stage mixing chamber 22, while a drain 49 connects the first stage mixing chamber to the upper part of drum 5!].

A drain 55 extends from the bottom of the drum to a trap 56, the opposite leg of which is connected to a duct 51, while the lower end of the latter communicates with the boiler The drain pipe 21 for the second stage funnel 25 is connected to a small chamber 66 into which the lower end of inclined pipe 40 extends, and an upwardly inclined duct 6| extends from the chamber 60 to the chamber 64 of the purger assembly 63 (Fig. 8).

- This assembly is of the type disclosed in my copending application Serial No, 167,402, filed October 5, 1937. A drop tube 65 of restricted internal diameter extends downwardly from the chamber 64, which receives gas through pipe 44. Bodies or globules of liquid propellant spilling over from the duct 6| entrap bodies of non-condensable gas in the tube 65, compressing the gas as they fiow downwardly throughthe tube. The lower end of the tube 65 is immersed in a body of liquid propellant in the well 61, the upper surface of this liquid propellant being exposed to the atmosphere.

A return duct 69 is disposed about the tube 65 and is connected to the pipe 51, there being a very small pressure equalizing vent I6 connecting the .upper part of duct 69 and the chamber 64.

A deflector 68 prevents gas from rising into the duct 69 from the open lower end of tube 65, such a defiecor being more fully disclosed in the copending application of Raymond W. Tibbetts, Serial No. 168,958, filed October L4, 1937. The arrangement of the spill-over connection between tube 6| and chamber 64 determines the'levels of the propellant in other parts of the system, as

will be more fully described, the level of this connection being indicated by the dot and dash line in Fig. 1. The condensed propellant received from drains 26, I4 and 21 passes to the receptacle 60 and from the latter may pass to the spill-over connection, thus being received by the purger. From thepurger the liquid propellant flows through pipe 51 back to the boiler, the height of the mercury in pipes 51 and 69 being su'ficient to balance the boiler pressure.

The pipes 34 and 35 form a trap A, while the pipes 6| and 46 also are included in a trap B, but the leg of this trap provided by pipe 46 has branches afforded by the pipes 34 and 35 of trap A, while pipe 42 may also be regarded as providing another branch of this leg.

Trap B is constantly receiving mercury from pipe 21 during normal operation of the system, and the spill-over connection between pipe 6| and chamber 64 definitely limits the height of the mercury in pipe 21. Thus a mercury column of constant height is automatically maintained in leg 6| of trap B, .while the total static pressure in this leg oil this trap is provided by this mercury column and the condenser pressure thereabove.

-Such a. total static pressure is balanced on the As a practical matter, the pressures above the branches of leg 40 do not exceed the condenser pressure which is always imposed on the mercury column in leg 6| of trap 13, so that the level of the spill-over connection determines the minimum height of the liquid in each of the branches 34, 35 and 42 of leg 40, this level being indicated by the dot anddash line of Fig. 1. When the pressures above the columns in ducts 35 and 42 are less than the condenser pressure, the liquid levels may rise above the level of the dotted line in Fig. 1. In either duct 34, 35 or 42 the level may rise above the level of the dotted line when liquid refrigerant displaces propellant.

Assuming that the system. is not in operation and that only mercury is contained in trap A, the level of the mercury in pipes 34 and 35 will be the same as that in pipe 6| of trap B, such a level ordinarily being even with the spill-over connection and being indicated by the dot and dash line of Fig. 1, and being shown in Fig. 6.

If the system is then started in operation, the pressure of the cooler falls below that of the condenser. Obviously, total pressures at opposite sides of trap A must be equal and mercury rises in pipe 35 as the pressure of the cooler falls relative to that of the condenser, while the mercury in pipe 34 remains at the level of the spill-over connection. The additional mercury received under such conditions by pipe 35 comes from the lower part of trap B which is receiving mercury from drain 21.

If the pressure difference between the cooler and condenser then falls, the liquid head in pipe 35 is automatically reduced and mercury is received by the lower part of trap B, causing mercury to overflow at the spill-over connection.

When the mercury columns are in the condition just described, liquid refrigerant may be received by pipe 34. The refrigerant piles up above the mercury in that pipe and, assuming conditions otherwise remain unchanged, this refrigerant displaces mercury in the pipe 34, this mercury passing into the lower part of trap B and causing mercury to overflow at the spill-over connection between pipe 6| and chamber 64. The refrigerant may thus continue to pileup in pipe 34 until it depresses the mercury sufiiciently to permit some of the refrigerant to rise into the opposite leg 35 of the trap. The refrigerant passing into pipe 35 rises to the top of the mercury in that pipe, displacing-some of the mercury in that leg of trap A, this mercury being received by the lower part of trap B. The refrigerant returns from pipe 35 to the cooler through tube 36 in the manner which has been described. It is thus evident that under average operating conditions the liquid column in pipe 34 may consistalmost entirely of refrigerant, while the column in pipe 35 may ordinarily consist of both mercury and refrigerant, such a condition being indicated in Fig.7.

It is evident that when the liquid heads are unchanged but mercury replaces refrigerant in one of the liquid columns of trap A, the height of the column will be reduced, since mercury is much heavier than the refrigerant which it replaces. Conversely, when refrigerant replaces mercury to provide the same liquid head, the liquid level will rise substantially.

It is now evident that the liquid head in pipe 6| equals that in pipe 34 plus that in pipe 46 below its connection to pipe 34, since the upper parts of pipes 6| and 34 intercommunicate through the condenser. The liquid level in pipe 34 is higher than the spill-over connection, howliquid head in pipe 35 is automatically adjusted to compensate for changes in the pressure-difference between the cooler and condenser, the difference between the liquid heads in legs 34 and 35 of trap A tending to equal this pressure difference.

The liquid column in pipe 42 is similarly automatically controlled, the liquid heads in that pipe sometimes differing from that in pipe 35 due to minor difierences between the vapor pressures in the upper parts of these pipes.

Very important advantages are afforded by such an arrangement over the return piping arrangements which have previously been used in systems of this character. Heretofore the propellant-containing trap in the return piping has had to co'ntain-sufiicient mercury to balance the maximum pressure differential between the cooler and the condenser. Accordingly, when this differential was not large, a relatively high column of the lighter refrigerant was required in the leg of the trap connected to the condenser in order to balance this quantity of heavier mercury so that the refrigerant could pass through the trap and into the cooler. Accordingly the condenser had to be at a substantial distance above the cooler and the height of the system was substantially greater than is required by the present arrangement.

Assuming there is no refrigerant in pipe 34 of the present system, the height of the mercury column above the juncture of pipes 34 and 35 is independent of pressure changes in the system, and by. proper design this height can be made very small; thus only a relatively short column of refrigerant may be needed to depress the mercury sufficiently to permit refrigerant to pass to the cooler. This arrangement permits the height of the refrigerant column in pipe 34 to be substantially constant and to be determined by the position of the juncture of the legs 34 and 35 of trap A relative to the height of the spillover connection between ducts SI and 63. Consequently a system of this character can be compactly arranged in a refrigerator housing of moderate height. The attainment of this important result is further materially aided by the arrangment of the downwardly extending pipe 43 between the upper end of pipe 42 and the connection to pipe 44, this arrangement permitting the cooler to be disposed a number of inches lower than would be the case were the upper part of pipe 42 directly connected to the pipe 44 below the cooler by a conventional horizontal connection.

Any mercury received by the refrigerant condenser fiows downwardly through the duct 34 to the trap A at the lower part of this duct. Mercury particles which pass into the cooler I I drain downwardly into the shallow trap provided by duct 44, piling up until mercury overflows into the drum 50. The latter also receives condensed mercury from the first and second stage mixing chambers. Obviously when the boiler pressure is normal, the mercury column in pipe 55 may have its upper surface below the drum 50. Ac-

cordingly mercury received by the drum passes into this pipe, returning through the trap 56 and the lower partof duct 51 to the boiler. It is thus evident that mercury is returned to the boiler from the drum 50 and through the upper portion of duct 51 which receives the mercury supplied to the purger.

When heat is supplied by burnei 2 at an abnormally high rate, thus tending to cause the boiler pressure to rise, mercury may rise into the drum 50. Due to the relatively large horizontal size of the latter, a substantial quantity of mercury is required in order to increase the mercury level appreciably in this drum. Thus as the mercury rises in the drum, the mercury level falls in the boiler, increasing the effective static head of the mercury column which balances the boiler pressure. If this. action continues, the mercury level in the boiler falls sufficiently so that a portion of the firebox In (Fig. 10-) is uncovered and the quantity of liquid mercury in contact with the firebox is thus reduced. Thereupon the boiler becomes less efficient so that the actual amount of mercury vapor supplied to the aspirator nozzles is not materially increased despite the higher rate of gas supplyto the burner. This arrangement furthermore prevents mercury from rising under such conditions into parts of the system where it would be undesirable.

The drum 50 not only has this function of aiding the automatic regulation of the boiler, but it also is efiective in automatically reducing the rate of evaporation in the cooler when the refrigerant freezes in the pipe 44. When the tube 36 and the upper part of pipe 44 are both blocked by frozen refrigerant, the condensed refrigerant can no longer pass to the cooler. Under these conditions, the refrigerant flows through the ducts 42 and 43 into the lower part of pipe 44,

displacing the mercury in the latter and passing into the drum 50. The upper part of this drum is connected by the pipe 49 to the low pressure portion of the refrigerant circuit, i. e., to the first stage mixing chamber. Accordingly, refrigerant vapor is then withdrawn from the drum 50 as well as from the cooler ll, so that part of the pumping effect of the mercury jet is being employed in pumping vapor from drum 50. Accordingly the rate of evaporation in cooler II is reduced so that its temperature rises, causing the ice which has formed in the pipes 36 and 44 to melt.

The drum 50 also has a third function when sludge collects in the cooler. As has been explained, it is desirable to employ an anti-freeze agent with the water to reduce the temperature which may be obtained in the cooler without resulting in freezing of the refrigerant. For this purpose an anti-freeze ingredient such, for example, as methyl Cellosolve or ethylene diamine, or mixturesof methyl Cellosolve and ethylene diamine may be employed in solution in'the water.

Since, however, ethylene diamine, if used in substantial quantities, tends to attack the walls of a conventional steel system, I prefer, in such a system, to use methyl Cellosolve alone with water or with a very small admixture of ethylene diamine, i. e., the latter not being over 5% of the weight of the solution.

The use of methyl Cellosolve, as commercially obtained, for an anti-freeze agent, however, increases the tendency of deleterious sludge to form inthe system. When the, mercury particles pass into the refrigerant condenser, some thin sludge suspension may form, this sludge tually form adeposit on the lower walls of the cooler, which has the consistency of thick mud. Asshown in Fig. 13, the cooler ll preferably is pro ided with lower walls which slope downwardly at a substantial angle toward the pipe 44, so

- that the heavy mud-like deposit can drain into pipe 44 which itself is of relatively large diameter to permit movement ofthe mud.

While for convenience of illustration, the lower part of pipe 44 is shown in the accompanying drawings as having a substantial length, it is practically desirable to make this portion of pipe 44 relatively short; thus requiring less mercury for this portion of the system. A reduction of the length of this pipe saves mercury not only directly due to the reduced length but also because' the pipe can then be made of smaller diameter and yet not afford an unduly high resistance to the movement of sludge to the drum-50.

with the arrangement disclosed herein, heavy mud-like sludge piling up on the mercury in the shallow trap formed by pipe 44 depresses the mercury in this trap and passes into the drum 50. The latter is connected to the first stage mixing chamber by the duct 49. Accordingly, under these conditions the more volatile portion of the heavy sludge, i. e., the refrigerant, is drawn into the first stage mixing chamber and the mercury residue fiows downwardly into the drain 55.

Preferably various warm portions of the system such as the mixing chambers and aspirator nozzles, the stack 3, the riser 5 and its branches, and the boiler may be enclosed in a casing I00 filled with discrete insulating materials, such as Cel-o-ceL- The mixing'chamber heads may conveniently be supported upon this casing, as shown in Fig. 1, and U-shaped brackets 95 (Figs.

'2, 3, 4 and 5) may be connected to these heads If desired, the pipes 35 and 35 shown in Fig.

1 may be omitted and the system be arranged so that the refrigerant always returns to the cooler through the pipe 42. Such an alternative arrangement is illustrated in Fig. 12 and the operation of the system with this arrangement is similar to that which has been described as taking place when the refrigerant in tube 36 of Fig. 6 becomes frozen.

In the operation of a system of this character, it is obvious that the mercury is boiled in the vaporizer I, the vapor passing upwardly through riser 5 and its branches 5 and 5 to the aspirator nozzles. Refrigerant vapor is drawn from the liquid body in cooler ll through the duct 8 into the first stage funnel, being there compressed and pumped into the interstage cooler l6, while condensed mercury is received from the funnel by drain l4. Condensing mercury particles settle on the bottom wall of chamber IS, a portion of this mercury being directed through pipe 20 to drain I4 and the remainder of the mercury passing into the vapor duct 2| andfrom the latter through the trap 5| and into the trap provided by the pipe 44. The refrigerant vapor from the duct 2| is further compressed frigerant passes into the pipe 34.

Non-condensable gases which are heavier than the refrigerant vapor pass into the drum 32 and are received by the pipe 44 whichsupplies them to the purger where they 'are compressed and exhausted to the atmosphere. The mercury received by the pipe 20 and by the drains l4 and 21, which are connected to the first and second stage funnels, respectively, may pass into the purger, there being effective in compressing the non-condensable gases, or this mercury may temporarily pass to the trap assembly associated with the cooler, for example, to provide additional mercury'fo'r -liquid heads in trap Aas has been described, Mercury from the second stage mixing chamber 22 passes'through pipe 5| and into pipe 44. This mercury may overfiow into drum 50 and pass from the same through pipe 55 into the return pipe 51 which also receives. the mercury from the purger. Mercury from the first stage mixing chamber is also received by drum 50 and may ordinarily drain into pipes 55 and 51..

Mercury columns in pipes 55 and 51 and in the return duct 69 of the purger automatically are maintained at heights which balance the boiler pressure. Under normal operating conditions refrigerant from pipe 34 depresses mercury in the trap A at the lower end of this pipe, so that the refrigerant rises to the duct 35 where partial vaporization thereof may occur so that slugs of refrigerant are spattered onto the surface of the liquid in cooler ll. Should freezing occur in this portion of the system, i. e., in the tube 36, the mercury at'the lower end of duct 34 will be further depressedso that the refrigerant will rise into pipe 42, being supplied from the latter through pipe 43 to the duct 44 and thence to thecooler. Should both the tube 36 and the uDDper part of pipe 44 become choked with frozen refrigerant, the refrigerant from pipe 34 willdepress the mercury in the trap 44 so that the refrigerant will findits way through this trap into the drum 50, being pumped from the latter to the first stage mixing chamber through the drain 49 so that'the first stage aspirator is then effective in pumpirig refrigerant vapor from the drum 50 as well as from the cooler Il.- Accordinglythe rate of evaporation in the latter is reduced and the temperature of the same rises so that the ice in its inlet pipes may melt.

Should the boiler temperature tend to be inordinately high, the mercurycolumn in pipe 55 will rise until mercury pills over into the drum 50, whereupon the mercury level in the boiler may start falling, thus causing an increase of the firebox is uncovered and the efilciency o1 the boiler is automatically decreased;

Should a substantial sludge deposit collect in thelower part of cooler ll, some of the sludge will find its way through the trap provided by pipe into the drum 50. Here the refrigerant is separated from the mercury particles, the refrigerant being vaporized and being drawn through the pipe 49 and the mercury coalescing into its normal state and being received by the return pipe 55. While the sludge in which the finely dispersed mercury particles are included is disadvantageous in refrigerating systems of the character described, this sludge has unusual properties that I believe will be advantageous in other fields.

It is evident that the present invention permits a compact system to be provided'to employ mercury vapor to pump refrigerant, while permitting low temperatures to be obtained in the cooler. The arrangement of the piping associated with the cooler not only permits the cooler to be near the level of the refrigerant condenser, if desired, but also facilitates vaporization of the anti.- freeze solution despite the tendency of a stronger solution to collect at the top of the liquid body in the cooler and despite the less volatile character of the anti-freeze agent. This arrangement of piping also automatically permits normal operation of the system automatically to be resumed if freezing occurs in the inlet piping adjoining the cooler. Furthermore, the assembly permits the automatic separation of mercury from sludge which may collect in the lower part of the cooler, thus avoiding clogging of pipes or the like. The arrangement of the drum 50 and associated parts of the system also permits a system of this character to be provided which will not be sensitive to abnormally high boiler temperatures. The arrangement of the separating chamber I!) permits adequate replenishment of the mercury supply in the trap assembly associated with the cooler and with the drum 50, and also assures the supply of some mercury to the purger under all operating conditions.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes allmodifications and equivalents which fall within the scope of the appended claims.

I claim:

1. Refrigerating apparatus of the class described comprising a propellant circuit and a.

refrigerant circuit, said circuits having a common part where propellant vapor pumps and compresses refrigerant vapor and where thepropellant vapor is condensed, said propellant circuit also including a boiler, a duct supplying propellant vapor from the boiler to said common part, and a return pipe directing condensed propellant from said common part to the boiler and containing liquid propellant to balance the boiler pressure, said refrigerant circuit also including a refrigerant condenser and a cooler, and a drum disposed between said common part and said re-- turn pipe, said drum having a cross-sectional size substantially greater than that of the return pipe, whereby, when the boiler pressure rises, the upper part of the liquid column is received in the drum and the height of the mercury column in the boiler is decreased in response to further increase in temperature of the boiler, so that the boiler pressure may be automatically maintained within rather closely predetermined limits despite variations in the amount of heat being su plied to the boiler.

2; Refrigerating apparatus of the class described comprising a propellant circuit and a refrigerant circuit, said circuits having a part in common where propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor is condensed, said propellant circuit also including a boiler, a duct supplying propellant vapor from the boiler to said common part, and a return pipe directing condensed propellant from said common part to theboiler and containing a column of liquid propellant to balance the boiler pressure, said refrigerant circuit also including .a refrigerant condenser and a cooler, and a drum disposed between saidcommon part and said retum pipe, said drum having a cross-sectional size substantially greater than that of the return pipe, whereby, when the boiler mercury in the boiler is decreased, so that the boiler pressure may be automatically maintained within rather close predetermined limits despite variations in the amount of heat being supplied to the boiler, a trap containing a body of the liquid propellant and having legs communicating respectively with the drum and cooler, the refrigerant circuit including a duct receiving condensed refrigerant from the refrigerant condenser and supplying the sameto the leg of the trap which is' connected to the cooler, whereby when the condensed refrigerant freezes between theconnection of the duct to said last-named leg and the cooler, the condensed refrigerant passes into the drum and is evaporated and pumped out of thedrum by the propellant vapor passing through-said common part, so that evaporation in the cooler is retarded and the temperature thereof tends to rise causing meltingof refrigerant in said leg of the trap, and whereby sludge may pass from the cooler to the drum and refrigerant be drawn from the sludge.

3. Refrigerating apparatus comprising a refrigerant circuit including a cooler and a con. denser, means to pump refrigerant about said circuit and to. cause a low pressure in the cooler and a higher pressure in the condenser, said cooler normally containing a body of liquid refrigerant, a cold, relatively less volatile layer of said refrigerant tending to collect at the surface of the body, the refrigerant circuit being arranged to direct condensed refrigerant from the condenser into the cooler so that the liquid in said layer is agitated and mixed with more volatile refrigerant, whereby its volatility is increased and the cooler efficiency enhanced.

4. Refrigerating apparatus comprising a refrigerant circuit including a cooler and a condenser, means to pump refrigerant about said circuit and to cause a low pressure in the cooler and a higher pressure in the condenser, said cooler normally containing a body of liquid refrigerant, a -cold, relatively less volatile layer of said refrigerant tending to collect at the surface of the body, the refrigerant circuit being arranged to spray condensed refrigerantfrom the condenser onto the surface of said liquid body, thereby impeding the formation of said layer.

5. Refrigerating apparatus comprising a refrigerant circuit including a cooler and a condenser, means to pump refrigerant about said circuit and to cause a low pressure in the cooler and a higher pressure in the condenser, said cooler containing a liquid body of refrigerant which includes a'morevolatile constituent and a less volatile constituent, the less volatile constituent, tending to collect more strongly in a cold layer of liquid at the upper surface of the liquid body, said refrigerant circuit being arranged to direct condensed refrigerant from the frigerant from the condenser, a trap having one leg provided by said duct, a tube connecting the upper part of the-other leg of the trap to the cooler above the surface of said'liquid body, the trap being arranged so that when refrigerant passes through the same, some of the refrigerant vaporizer containing a body of mercury, a return duct extending from the condenser to the cooler, said duct having a trap with a pressure balancing column of propellant in one leg, a section of the duct extending downwardly from said leg to a connection to the cooler below the latter, said cooler containing a body of liquid refrigerant comprising water and an anti-freeze agent in solution therewith, the solution tending 'to be I stronger in the anti-freeze agent in a layer at the upper surface of the liquid body, the returning refrigerant received through said connection tending to break up said stronger layer, means connected to said trap automatically to vary the height of the pressure balancing column in-response to changes in the pressure difference between the cooler and condenser, a chamber arranged to receive sludge from said connection,

I and a pipe connecting the chamber to the low pressure portion of said refrigerant circuit,

whereby the refrigerant may be drawn from the sludge.

'8. Refrigerating apparatus comprising a re- 40 frigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with said refrigerant circuit wherein refrigerant vapor from the cooler is entrained in a stream of the propel ant vapor from the vaporizer, said vaporizer con- .taining a body of mercury, said refrigerant circuit including a return pipe extending downwa'rdly from the condenser, said pipe providing one leg of a trap,the opposite leg of the trap containing a pressure-balancing column of propellant and extending upwardly, the top of the last-named leg communicating with a tube which is connected to the cooler above the surface 'of the liquid refrigerant contained therein, whereby slugs of refrigerant may be emitted from the tube onto said surface, the lower end of the pipe being connected to a duct containing a second pressure-balancing column, a second duct connected to the bottom of the cooler, a downwardly extending continuation of the first duct having a connection with the second duct substantially below the cooler, whereby, when refrigerant freezes in the-tube, 'the returning refrigerant may enter the cooler through said ducts.

cuit wherein refrigerant vapor from the cooler 70 is entrained in a stream of the propellant vapor from the vaporizer, said vaporizer containing a I body of mercury, a return duct extending from the condenser to the cooler, said duct having a trap with a pressure-balancing column of propellant in one leg, a section of the duct extending downwardly from said leg to a connection to the cooler below the latter, and means connected to said trap automatically to vary the height of the pressure-balancing column in response to changes in the pressure difference be- 5 tween the cooler and condenser,

10. Refrigerating apparatus comprising a, refrigerant circuit including a cooler and a condenser, means for pumping the refrigerant from the cooler to the condenser and to afford a low 1.0

pressure in the former and a higher pressure in the latter, said circuit having a duct extending from the condenser to the cooler, said duct including a trap having a leg containing a column of liquid to'balance the pressure difference be- 15 tween the cooler and condenser, the liquid refrigerant from the condenser piling up in the opposite leg of the trap so that it may have sufficient head to permit refrigerant to rise through said column of liquid, and means connected to the trap and to the condenser automatically effective to vary the height of said column in response to variations in said pressure difference.

11. Refrigerating apparatus comprising a refrigerant circuit including a cooler and a con- 25 denser, means for pumping the refrigerant from the cooler to the condenser and to afford a relatively low pressure in the former and a higher pressure in the latter, said .circuit having a duct extending from the condenser to the cooler, said 30 duct including a trap having a leg containing a column of liquid to balance the pressure difference between the cooler and condenser, the liquid refrigerant from thecondenser piling up in the opposite leg of the trap so that it may have sufliclent head to permit refrigerant to rise through said column of liquid, a second trap containing a body of the liquid and having one leg connected to the lower part of the firstnamed trap, the second trap having its oppo-.4o

site leg provided with a spill-over connection 'determiningthe level of liquid in that leg of the trap, the last-named leg of. the second trap being connected to the condenser and subject to the condenser pressure, saidsystem being 5 arranged to direct liquid into the lower part of the second trap, whereby the liquid column in said first-named trap may have a head above the spill-over connection which is automatically varied to compensate for changes in the pressure difference between the cooler and condenser.

12. 'A system of the class described comprising a heavy liquid circuit and a light liquid circuit having two portions at different pressures, said last-named circuit including a trap having legs 55 connected respectively to each of said portions, the leg connected to the low pressure portion containing a column of heavy liquid tending to balance pressure differences between said portions, the opposite leg containing a column of 3 lighter liquid which may become high enough to permit some of the lighter liquid to leak through the trap and rise through the column .of heavy liquid, said heavy liquid circuit including a trap having one leg connected to the lower part of the first-named trap and having its, opposite leg provided with a spill-over connection, said connection communicating with the high pressure portion of the light liquid circuit, the heavy liquid rising'from the second-named'trap 7 into said heavy liquid column in the first trap when the pressure difference between saidportions rises and flowing from said first-named trap into the second trap when the pressure difference falls, whereby the height of said heavy 5 liquid column above the spill-over connection in the first trap is automatically adjusted in accordance with varying pressure differences between said portions.

13; Refrigerating apparatus comprising a refrigerant circuit including a condenser and a cooler, said cooler containing a body of relatively light refrigerant, a propellant circuit comprising a vaporizer and a part in common with the refrigerant circuit where propellant vapor is efiective in drawing refrigerant vapor from the cooler, compressing the same, and pumping the same to the condenser, and where the propellant is condensed, said refrigerant circuit also including a duct extending from the condenser to the cooler, said duct having a trap with one leg connected to the cooler and containing av column of the propellant tending to balance the difference in pressure between the cooler and condenser, the propellant circuit having a trap receiving'condensed propellant from said common part, said second-named trap having one leg connected to the lower portion of the firstnamed trap and having its opposite leg provided with a spill-over connection from which the propellant is returned to the vaporizer, the propellant column in the first-named trap being automatically adjusted in accordance with varying differences in pressure between the coolerand condenser, the liquid refrigerant in the other leg of the first-named trap piling up to leak through the trap and rise through said heavy liquid column and thus return to the cooler.

14. Refrigerating apparatus of the class de-" scribed comprising a refrigerant circuit including a condenser and a cooler, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where the propellant draws refrigerant vapor from the cooler,

compresses the vapor, and pumps the same to the condenser, a drain extending downwardly from the cooler and connected to-the propellant circuit through which stray propellant may be returned to the propellant circuit, a duct extending from the condenser to a connection with I said drain, said duct having a trap therein, a second trap having a leg connected to the lower part of the first-named trap and receiving condensed propellant from said common part of the circuits, the opposite leg of the second trap having a spill-over connection, the'first-named trap having a leg containing a column of the propellant tending to balance the pressure difference between the cooler and condenser, the upper part of said leg being above the connection of the duct and drain, the duct having a section extending downwardly to its connection with said drain.

15. Refrigerating apparatus of the class described comprising a refrigerant circuit including a condenser and a cooler, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where the propellant draws refrigerant vapor from the cooler, compresses thevapor and pumps the same to the condenser, a drain extending downwardly from the cooler and connected to the propellant circuit through which stray propellant may be returned to the propellant circuit, aduct extend ing from the condenser to a connection withsaid drain, said duct having a trap thereih, a second trap having a leg connected to' the lower part of the-first-named trap a; 1 receiving condensed propellantfrom said common part of the circuits, the opposite leg of the second trap having a spill-over connection, the first-named trap having a leg containing a column of the the circuits to said third trap.

16. Refrigerating apparatus of the class described comprising a propellant circuit and a refrigerant circuit, said circuits having common partswhere propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor condenses, said parts being in successive portions of the refrigerant circuit and in parallel portions of the propellant circuit, the refrigerant circuit also including a cooler, a condenser, an interstage cooler between said common parts, a pipe extending from the interstage cooler to the second of said common parts, and a receptacle in said pipe providing a portion of enlarged cross section where propellant particles may more readily collect, a trap receiving propellant from said common part, said trap having one leg provided with a spill-ever connection, the opposite leg of said trap being connected to a trap in the refrigerant circuit between the condenser and the cooler, said lastnamed trap having one leg containing a pressure-balancing liquid column, said leg having its upper end connected with the cooler, the

opposite leg of the trap normally containing condensed refrigerant which, when piling up in this leg of the trap, may pass through the trap, rising into the liquid column and return to the cooler, the height above the spill-over connection of said liquid column in the first-named leg of the trap being automatically varied in accordance with variations in difierencesbetween the cooler and condenser pressures, the liquid in said column being received. from the firstnamed trap and the receptacle when the height of the column increases, and the liquid from the column displacing liquid in the first-named trap and causing some of the liquid from that trap to pass through the spill-over connection. when the height of the column decreases.

17. Apparatus of theclass described comprising a propellant circuit and a refrigerant circuit, said circuits having common parts where propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor condenses, said parts being in successive portions of the refrigerant circuit and in parallel portions of the propellant circuit, the propellant circuit also including a boiler and return piping connecting said common parts to the boiler, the refrigerant circuit also including a cooler, a refrigerant condenser, an interstage cooler between saidcornmon parts and a pipe extending from the interstage cooler to the second of said common parts,

a receptacle in said pipe providing. a portion of' enlarged cross section where propellant particles may more readily collect.

18. Apparatus of the class described comprising a propellant circuit and a refrigerant circuit,

said circuits having common parts where propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor condenses, said parts being in successive portions of, the refrigerant circuit and in parallel portions of a receptacle in said pipe providing a portion of enlarged cross section where propellant particles may more readily collect, the refrigerant circuit also including a trap between the condenser and cooler, the trap being arranged to c receive condensed propellant from said receptacle.

19. Apparatus of the class described compris-- ing a propellant circuit and a refrigerant circuit, said circuits having common parts where propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor condenses, said parts being in successive portions of the refrigerant circuit and in parallel portions of the propellant circuit, the propellant circuit also including a boiler and return piping connecting said common parts to the boiler, the refrigerant clrcuit also including a cooler, a refrigerant condenser, an interstage cooler between said common parts, and a pipe extending fromthe interstage cooler to the second of said common parts, a receptacle in said pipe providing a portion of enlarged cross section where propellant particles may more readily collect, the refrigerant circuit also including a trap between the condenser and cooler, the system having a purger receiving propellant liquid and arranged to pump non-condensable gases from the system, said receptacle having connections arranged to assure part of the propellant draining from the trap and a part thereof draining to the purger.

20. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler, a condenser and means to pump refrigerant about said circuit, said circuit also including a return duct extending from the condenser to the cooler, said duct having a trap therein arranged so that a column of liquid refrigerant may pile up in one leg of the trap to overbalance a column of liquid in the opposite leg thereof andmay thus pass through the trap, the last-named leg of the trap extending upwardly to a region near the top of the cooler,

the duct including a pipe section extending downwardly from the top of the last-named leg of the trap, and a pipe extending downwardly from the bottom of the cooler and communicating with the last-named pipe section below the cooler, whereby condensed refrigerant passing through the trap may pve upwardly through the top' of the last-name leg of the trap downwardly through the pipe section and upwardly through the last-named -pipe thus returning to the cooler.

21. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler, a condenser and means to pump v refrigerant about said circuit, said circuit also including a return duct extending from the condenser to the cooler, said duct having a trap therein arranged to provide one leg containing a column of liquid refrigerant and an opposite leg to contain a column of press....: balancing liquid so that the refrigerant may pile up in the firstnamed leg to overbalance said column sufliciently to permitrefrigerant to pass through the trap and to the top of said column, the upper part of the last-named leg of the trap extending up- LYMAN F. WHITNEY. 

